Poor traction with Atlas MP15DC switcher

[Biased turkey]

I cleaned the track with my Atlas track cleaning car, I cleaned the wheels using the standard procedure ( 1 truck on a paper towel with alcohol and the 2nd truck on a DC powered piece of track ) , I swaped both trucks and still that MP15 stalls on turnouts at low speed . I even cleaned the flat brass springs that transmit the current from the trucks to the frame. Sometimes on straight tracks it stops but the light are still on and the wheels are spinning but the engine doesn't move ( I know that in this case it's not a contact problem because the wheels are spinning ).

Any idea ? Wheels out of gauge ?
It is locomotive dependent because my Life-Like SW9/1200 and my Atlas GP7 run perfectly.
Tia for any suggestion.

 

[Biased turkey]

Just to update about the situation: yesterday evening I replace the front original coupler with a micro-Trains one and it soloved the stalling problem ( The trip pin of the Atlas coupler was too low and hitting some part of the turnout ( I want to standardize all my couplers anyway ).
I removed both trucks and adjusted the 2 long brass wipers conducting the current from the trucks to the frame. That took care of the electrical problem.
I checked the wheels distance with the Micro-trains gauge and found it to be out of gauge ( too small ) could that explain the poor traction problem ? ( with more than 3 boxcars the engine wheels are spinning )

 

[CAS]

I replace the front original coupler with a micro-Trains one and it soloved the stalling problem

I changed my couplers to MT's almost right away. Atlas couplers and MT couplers don't operate very well together, IMO. So all my loco's and rolling stock get MT's couplers before the go onto the layout.

I'll have to check my wheel distance with the MT guage one of thesse days, then. But i haven't been having any problems with the wheels spinning.

CAS